1. If you want to vote for 2 delegates you will need to split your ARK in 2 ARK address and vote for the ones you want from this 2 ark addresses ( 1 ark address can vote for 1 delegate at a time)
2. Yes, if you sent more Ark to address you are voting with it will automatically reflect in bigger voting weight (and depending on the delegate you are voting for, bigger share of rewards)